The AR-15 is very good at one thing

The AR-15 is very good at one thing: not hunting, but engaging the enemy at a rapid rate of fire.

On Dec. 24, in Webster, N.Y., an ex-con named William Spengler set fire to his house and then shot and killed two responding firefighters before taking his own life. He shot them with a Bushmaster AR-15-style semiautomatic rifle — the same weapon that Adam Lanza used 10 days earlier when he shot and killed 26 people at Sandy Hook Elementary. James Holmes used an AR-15-style rifle with a detachable 100-round magazine this past summer when he shot up a movie theater in Colorado

Three makes a trend, as we all know, and many people have reacted by suggesting that the federal government should ban the AR-15 and other so-called assault weapons. Gun advocates have responded with exasperation, saying that, despite appearances, AR-15-style rifles are no more dangerous than any other gun. In a piece this week on humanevents.com titled "The AR-15: The Gun Liberals Love to Hate," NRA president David Keene blasted those critics who "neither understand the nature of the firearms they would ban, their popularity or legitimate uses." Keene noted there are several valid, nonmurderous uses for rifles like the AR-15 — among them recreational target shooting, hunting and home defense — and argued that law-abiding firearms owners shouldn't be penalized because of homicidal loners who use semiautomatics like the AR-15 for criminal purposes.

I generally consider myself a Second Amendment supporter, and I haven't yet decided where I stand on post-Newtown gun control. But I nevertheless find Keene's arguments disingenuous. It's odd to cite hunting and home defense as reasons to keep selling a rifle that's not particularly well suited, and definitely not necessary, for either. Bolt-action rifles and shotguns can also be used for hunting and home defense. Unfortunately, those guns aren't particularly lucrative for gunmakers. The lobby's fervent defense of military-style semiautomatic weapons like the AR-15 seems motivated primarily by a desire to protect the profits in the rapidly growing "modern sporting rifle" segment of the industry.

The AR-15 was designed in 1957 at the behest of the U.S. Army, which asked Armalite to come up with a "high-velocity, full and semi auto fire, 20 shot magazine, 6lbs loaded, able to penetrate both sides of a standard Army helmet at 500 meters rifle," according to ar15.com. When it entered Army service in the 1960s, it was renamed the M16, in accordance with the Army Nomenclature System. "AR-15" came to refer to the rifle's semiautomatic civilian equivalent. From 1994 to 2004, AR-15-style rifles were subject to the now-expired Federal Assault Weapons Ban. Since then, the rifle and others like it have become tremendously popular. Last month, I estimated that upwards of 3.5 million AR-15-style rifles currently exist in the United States. People like the rifle because it is modular and thus customizable, because it is easy to shoot and because carrying it around makes you look like a gangster.

But the AR-15 is not ideal for the hunting and home-defense uses that the NRA's Keene cited this week. Though it can be used for hunting, the AR-15 isn't really a hunting rifle. Its standard .223 caliber ammunition doesn't offer much stopping power for anything other than small game. Hunters themselves find the rifle controversial, with some arguing AR-15-style rifles empower sloppy, "spray and pray" hunters to waste ammunition.

In terms of repelling a home invasion — which is what most people mean when they talk about home defense — an AR-15-style rifle is probably less useful than a handgun. The AR-15 is a long gun, and can be tough to maneuver in tight quarters. When you shoot it, it'll overpenetrate — sending bullets through the walls of your house and possibly into the walls of your neighbor's house.

AR-15-style rifles are useful, however, if what you're trying to do is sell guns. In a recent Forbes article, Abram Brown reported that "gun ownership is at a near 20-year high, generating $4 billion in commercial gun and ammunition sales." But that money's not coming from selling shotguns and bolt-action rifles to pheasant hunters. In its 2011 annual report, Smith & Wesson announced that bolt-action hunting rifles accounted for 6.6 percent of its net sales in 2011 (down from 2010 and 2009), while modern sporting rifles (like AR-15-style weapons) accounted for 18.2 percent of its net sales. The Freedom Group's 2011 annual report noted that the commercial modern sporting rifle market grew at a 27 percent compound annual rate from 2007 to 2011, whereas the entire domestic long gun market only grew at a 3 percent rate.

The AR-15 is very good at one thing: engaging the enemy at a rapid rate of fire. When someone uses it to take out 26 people in a matter of minutes, he's committing a crime, but he isn't misusing the rifle. That's exactly what it was engineered to do.